Over the past several decades, some technologies have been developed to control or measure the flow of fluids. Design of many aerospace, chemical, and mechanical systems have been dependent on assessment of amount of fluid passed a certain point in the process or in the equipment. However, the available methods or equipment are most efficient in the conventional ranges used in the established industry.
In microfluidic devices, as used in emerging technologies, the features and passages of flows are extremely small, hence, extra forces come to play and appear in the governing laws of the fluid flow. Furthermore, in life sciences, samples and reagents are frequently expensive and/or available in very limited quantities.
Capillary-driven microfluidic chips enable minute amounts of biological samples to be analyzed. These differences have created the necessity of new designs for specialized flow control. Chips have been developed by IBM® for high-sensitivity and low-volume immunoassays, reserved for high-end assays.
A high level of expertise and too many steps are required for taking advantage of the full spectrum of possibilities offered by micromosaic immunoassays. They necessitate two expensive chips, which poses a strong obstacle to automation which is critically needed for using these chips and getting high-quality data. Each chip must be cleaned and treated with chemicals to have appropriate surface chemistry.
New chips, which are being made, are very large and therefore expensive. Furthermore, these chips cannot be reused indefinitely because of contamination, dust particles, scratches, etc. In order to use only one chip for these devices, the microchannels on the chip's surface need to cross each other. Microfluidics having crossing channels can bring various liquids for analysis in one area.
However, the liquids must be passed in the right sequence, at the right time and using the right volume of solution. Typically, actuators or valves are used to stop or let a liquid pass in a microchannel. As one of their drawbacks, actuators are expensive to fabricate and necessitate peripheral equipment. Magnetically actuated valves are simpler to fabricate and actuate than many other types of valves. The act of actuation can be done in them by as simply as applying an external magnetic field.
This is an issue for magnetic valves that are used to control the flow of liquid at areas where microchannels cross.